The present invention generally relates to a process for massively producing tape type flexible printed circuits with sprocket holes, particularly to a flexible fabrication process for massively producing tape type flexible printed circuits which are applied to electrical connectors, such as electrical connections between driver and display panel, and between foldable electronic components, also even as a chip carrier of semiconductor package like Chip-On-Film package or tape carrier package, wherein the tape width of the tape type flexible printed circuits can be selected in a very flexible manner.
Flexible printed circuits that can be bent and twisted are widely applied to the electrical connection between two electronic components. A common flexible printed circuit is installed in a LCD (liquid crystal display) module as an electrical connection between LCD panel and rigid printed circuit board.
A method for manufacturing flexible printed circuits is disclosed in U.S. Pat. No. 6,210,518, but that has not mentioned how to massive produce flexible printed circuits, so that the manufacturing cost of flexible printed circuits cannot be decreased effectively. Besides, among advanced electronic products the flexible printed circuits of beyond 0.2 mm in thickness are no longer satisfied by market, so that how to massively produce the flexible printed circuits under 0.2 mm in thickness (flexible tape type) is a point to be solved imperatively.
It is a main object of the present invention to provide a process for massively producing tape type flexible printed circuits. The metal traces and cover layer are formed on a flexible insulation tape with big area in reel-to-reel fashion, and the flexible insulation tape is cut along the parallel lines where sprocket holes arrange on to become several strips of small flexible circuit tapes with variable width, then reeled in reels. Therefore, it is possible to massively produce tape type flexible printed circuits with low cost and with variable width by means of a set of manufacturing system.
In accordance with the process for massively producing tape type flexible printed circuits, a copper foil and a dry film are sequentially bonded on a flexible insulation tape which is made of polyimide, polyester, polyethylene naphthalate, liquid crystal polymer, or Teflon in reel-to-reel fashion, and a first standard point is set on the flexible insulation tape. Thereafter, the copper foil is etched to form metal traces, and sequentially cover films are attached on the flexible insulation tape. Then surface treating is executed. Next, the sprocket holes are formed on the flexible insulation tape by punching and the flexible insulation tape is cut along the parallel lines where the sprocket holes arrange on to become several strips of narrow flexible circuit tapes, then reeled in reels. Each flexible circuit tape has a plurality of flexible printed circuits between two sides of sprocket holes. It is preferable that there is an electrical test step right after cutting step for testing the flexible printed circuits and marking the defectives.